The Principal is the head of the prestigious Harris Academy, the school that serves as the main setting of the series. He appears early in the story when Kunimatsu, a boy who has recently settled in Tokyo and who dislikes school while loving fighting and eating, has not yet been enrolled. The Principal personally approaches Kunimatsu and urges him to join Harris Academy, and this direct invitation is what brings the protagonist into the school and sets his school life in motion.

Within the academy, the Principal holds the highest position in the school hierarchy and is shown as a figure who watches over the entire school community, including both teachers and students. His role in the narrative is primarily institutional: he acts as the authority who admits Kunimatsu into the school, and he otherwise remains an overseeing presence rather than a participant in the students' day-to-day adventures, arguments, and baseball activities. His most significant relationship is with Kunimatsu, whom he personally recruits even though the boy openly dislikes school, while his connection to the wider student body is more distant and defined by his position. His motivations are not explored in great depth, but his willingness to appear before Kunimatsu and press him to enroll shows a direct and personal interest in the boy's admission. In terms of ability, the Principal exercises the powers of his office: he can decide on enrollment and he carries responsibility for maintaining the order and smooth running of the academy. Throughout the series he functions as a steady supporting figure whose key decision helps place the protagonist at the center of the school's world.